The season brings endless rain and unbearable humidity, where sweat forms even when standing still. Manabu is cleaning the house together with his mother, Chiharu. As they work, Chiharu becomes drenched in sweat, her swaying hips catching Manabu's eye. He freezes, speechless at the sight. "M-Mom... you're sweating so much..." he murmurs, as Chiharu raises her arms, exposing her damp, glistening armpits to Manabu. At that moment, something inside Manabu snaps completely.